Vehicle perception relates to sensing information around a vehicle related to the operation of the vehicle. Vehicle perception acts as eyes of the vehicle to feed itself with knowledge of what is happening around it. In-cabin perception is an important aspect of vehicle perception because the state and activity of the driver and passengers provide crucial knowledge in terms of assisting the driver driving safely, and in providing an improved human machine interface (HMI). With the awareness of the driver's activities, the vehicle can determine whether the driver is distracted, fatigued, distressed, raged, or inattentive so it may provide alerts or support mechanisms to keep the driver safe from accidents and to improve the comfort level of the driver. Automated activity recognition is an emerging technology. Current activity recognition methods rely heavily on powerful computing resources that can consume a large amount of energy while occupying a large amount of space of the vehicle. The present inventors have recognized a need for improved activity detection for vehicle perception.